1. Field of the Invention
The present invention relates, in general, to a mass measurement system and method and, more particularly, to a mass measurement system and method using the measurement of the frequency shift of a vibrator, which measure a frequency shift according to the variation of mass added to a vibrator, thus precisely measuring the mass of a sample, especially in a gravity-free environment.
2. Description of the Related Art
The present invention relates a mass measurement system and method in a gravity environment, as well as a gravity-free environment, but, hereinafter, an embodiment implemented, in particular, in a gravity-free environment is described.
Generally, the inside of a spacecraft traveling in space is in a micro gravity environment having little gravity, or in a gravity-free environment. In order to measure the mass of a sample, which is a space experiment object, such as a rat, in a spacecraft having a micro gravity or gravity-free environment, the mass of the sample is measured using a device generally known as a so-called “space mass measuring device”, not a typical balance for measuring mass in a gravity field.
Hereinafter, a conventional mass measurement device in a gravity-free environment, which is designated as a so-called “space mass measuring device”, is described.
FIG. 1 is a conceptual configuration view showing conventional mass measurement in a gravity-free environment.
The conventional mass measurement in a gravity-free environment of FIG. 1 is performed using a spring 10 having a predetermined elastic modulus k, a sample S connected to the spring 10, and a frequency counter (not shown) connected to the sample S to measure the frequency of the spring 10.
In a mass measurement method performed by the conventional mass measurement device in a gravity-free environment, external force is applied to the sample S to cause vibration, so that the frequency of the sample S connected to the spring 10 is measured by the frequency counter (not shown).
Further, the mass of the sample S is measured using a calculation program based on the measured frequency of the spring 10 and the elastic modulus k of the spring 10.
However, the above-described conventional mass measurement method in a gravity-free environment causes the following problems.
First, the mass of the sample S measured by the conventional mass measurement technology in a gravity-free environment in FIG. 1 has a large error because it is difficult to precisely measure a vibration period due to the damping effect of the measurement device itself.
Second, if the above-described mass measurement method in a gravity-free environment is used, there is a problem in that repeated measurements must be performed for a long period of time so as to perform precise measurement.
Third, a vibration system itself using the mass measurement device of FIG. 1 is a non-linear system, so that it is very difficult to obtain the mass of a sample S on the basis of a vibration period, and measurements are subject to error.
Further, according to the conventional mass measurement method currently used in a spacecraft, it is known that an error of about 1% occurs at the time of measurement, so that the method is not suitable for precise measurement and it has actually been used for a method of roughly measuring the weight of an astronaut.
Fourth, the conventional mass measurement method is limitedly used to approximately measure large masses such as the weight of an astronaut (for example, a mass of about 100 kg). That is, there occurs the problem in that the conventional mass measurement method is not suitable for the precise measurement of a small mass (for example, a mass of 5 kg or less) for space experiments, the necessity of which is recently increasing, for example, precise measurement having an error of 1% or less.
Accordingly, since precise measurements prior or subsequent to an experiment on a space experiment sample are mainly performed on earth, a large inconvenience is caused, thus the precision and efficiency of space experiments are greatly limited.